To add two and two

     Today I call attention again (as in my post for 6 January, 2015) to the extensive  Science-Poetry collection edited by Norman Hugh Redington and Karen Rae Keck. Mathy (rather than bawdy) limericks are featured in the collection; for example, this one by an unknown author:

       There was an old man who said, "Do
       Tell me how I'm to add two and two?
            I'm not very sure
            That it doesn't make four --
       But I fear that is almost too few."